I think alot is down to personal preference - I always look for well marked/coloured birds, not always the biggest birds but usually the fittest looking ones with the right shaped body and carriage, the drake is very important as he's half your flock genetically when breeding so careful selection is needed for him - I put all my boys together in a pen and then it's easier to compare them all! If you're into the showing side of things then reading up on the breed standard for your breeds can help a bit and picking the ones which match the closest, if you're after productivity more than anything else then obviously the choice will be made for you by the most productive birds being the ones to breed from, you'll also find when you actually look at them as a bunch the same birds will stand out time and time again - those are the ones to pick.
